Counterbalance for oil-well pumps



Oct. 1, 1929. s. 1.. CRAWSHAW 1,729,737

COUNTERBALANCE FOR OIL WELL PUMPS Filed Sept. 23, 1927 2 Sheets-Sheet 1 Fi .3. F794. Fi 5. Fig. 6.

INVENTOR ATTORNEY Zap/ en L. Draws/Yaw.

Get 1, 1929s s. L. cRAwsHAw GOUNTERBALANCE FOR OIL WELL PUMPS Filed Sept. 25, 1.927 2 Sheets-Sheet '2 Fig. 8.,

INVENTOR 5119p (27? L Cmwsizaw.

AT'TORNEY Patented a. 1, 1929 UNITED STATES PATENT OFFICE STEPHEN L. CRAWSHAW, DALLAS, TEXAS, ASSIGNOR, BY MESNE ASSIGNMENTS, TQ WESIING-HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF rnmrsrnvama COUNTERBALANOE FOB OIL-WELL PUMPS Application filed September 23, 1927. Serial No. 221,597.

The invention relates to counter-balancing devices and more particularly to means for counter-balancing the apparatus used for pumping oil from wells.

5. The usual form of uinping equipment for I use in pumping oil rom wells comprises a pump tubing that extends into the well from the surface of the ground. A plunger is disposed in the lower end of the tubing and is adapted to be operated b means of a string of sucker rods. Thesuc er rods are caused to reciprocate by means of a walkin beam that is pivoted near its center on a amson post and is actuated by a crank and a pitman rod connected to the end of the beam opposite the end to which the sucker rods are fastened.

When the pump is in operation, the forces which must be overcome by the walking beam and its driving mechanism during the up ward stroke of the lunger comprise the force necessary to lit the weight of the sucker rods and the pump plunger and the weight of the column. of fluid being lifted,

mechanism and the forces necessary to overcome the inertia of the pumping equipment during the accelerating period. During the down stroke, the weight of the sucker rods and pump plunger is sufficient to overcome the-forces of friction and inertia and, therefore, the actuating force in the walking beam ma be considered as a negative quantity.

herefore, it will be understood that the forces necessary to actuate the pumping mechanism are of a very uneven or jerky character, and it is obvious that 'a prime mover for operating the pumping mechanism must necessarily be of a capacity much greater than the actual power'utilized in the pumping operation in order to be capable of exerting the maximum force necessary to lift the pump plunger. 1

It is further apparent that the uneven or jerky nature of the movement of the pumping mechanism is very detrimental to thev prime mover and the transmission mecha: nism.

It is an object of my invention to provide a counter-balancing mechanism for oil-well the frictional resistance of the pumping pumps that shall be adapted to neutralize the lnherent unbalance in the standard wellpumpmg apparatus.

other object of the invention is to provide a counter-balancin mechanism for oilwell pumps that may e adjusted tovary the counter-balancing effect.

A further object of the invention is to provide a counter-balancing mechanism that may be adjusted in such manner that the counter-balancing effect is substantially neutralized and the mass of the device so discounter-balancing mechanism shown in Fig. 1,

Figs. 3, 4, 5 and 6 are views in elevation of the adjustable leaf weights of the counterbalancing mechanism shown in Fig. 1,

Fig. 7 1s a view, in end elevation, of a crank arm and an integral counter-balancing weight that constitutes part of the mechanism shown in Figs. 1 and 2,

Fig. 8 is a view, in side elevation, of the crank arm and weight shown in Fig. 7, and

Fig. 9 is a view, in elevation, of a standard oil-well-pumping apparatus illustrating the manner in which the invention may be utilized.

Referring to Fig. 9 of the drawing, a standard oil-well-pumping apparatus, in conjunc tion with which a counter-balancing mechanism embodying the invention may be utilized, comprises a derrick 1 of the usual construction that is provided with a derrick floor 2 having sills 3-that extend some distance to one side of the errick to provide the working platform" for; supporting the pump-actuating appapatus.

As shown/1n the drawings, the pumping apparatus comprises a Samson post 4 that is erected upon'the sills 3 at one side of the derrick 1 and serves to support a walking beam 5 that is pivotally mounted thereon by means of a pin connect1on 6; One end of the walking beam 5 extends from substantially nected to the end of the walking beam 5 by means of a stirrup 9. In order that the sucker rods 8 may be givena reciprocating motion, the other end of the walking beam '5 is connected to a pitman rod 12 by means of a stirrup 13. The lower end of the pitman rod 12 is adjustably connected, by means of a crank pin 14, to a. crank arm 15 that is mounted on a crank shaft 17 of a geared pumping unit 18 that may be driven by means of an electric motor (not shown) or othersuitable engine.

Referring now to Figs. 7 and 8, the crank arm 15 constitutes an integral part of a counterbalancing weight 21: that is further provided with a hubportion 22 which is adapted to be pressed or otherwise placed upon the shaft 17 and secured thereto by means of a key 23. The hub portion 22 is provided with a flange 24 having a number of spaced holes 25 disposed in a circle having its center at the center of the hub 22.

The counterweight member 21 is formed in the shape of a sector of a disc, and the hub 22 is so positioned that the sector is normally disposed to rotate about its geometrical center.

In order to provide means for adjusting the balancing mass and its angular relation to the crank arm 15, a pair of adjustable leaf weights 31 and 32 are provided, each of which has the shape of' a sector of a disc having substantially the radius and thickness of the balancing weight 21 and is of such proportions that, when placed edge to edge, the weights 31 and 32 together constitute substantially a duplicate of the weight 21, both as regards their general outline and combined mass. Each of the weights 31 and 32 is provided with oflset collars 33 that are adapted to be journalled on the hub portion 22 of the weight 21. The collars 33 are olfset approximately one-half the thickness of the weights 31 and 32 in order that the weights may both lie in the same plane and thereby occupy a minimum amount of space between the crank 15 and the geared pumping unit 18.

Bolt holes 34 are provided in each of the weights 31 and 32, at the proper distance from the center of rotation thereof, to permit them to be brought into alinement with the holes 25 in the flange 24 of the weight 21. Bolts 35 are provided in order to secure the weights 31 and 32 rigidly to the flange 24.

The adjustment of the leaf weights may be readily accomplished by first turning the shaft 17 to bring one of the weights to its lowest position. -The bolt 35 may then be easily removed without danger of the weight falling. The shaft 17 may then be turned to having the desired hole 25 in the flange 24 into alinement with the hole 34 in the leaf weight, and the bolt 35 inserted to secure it in place. This method may then be repeated for the other weight. 4

It will be observed that the weights 31 and 32 may be brought into axial alinement with the weight 21 and secured in this position by inserting the bolts 35 through the holes 25 that are disposed on each side of the crank arm 15. When placed in this position, the weights 31 and 32, together with the weight 21, constitute a relatively large unbalanced mass that may be considered as being concentrated atv the crank arm 15.

On the bther hand, the weights 31 and 32 may be turned to positions diametrically opposite the weight 21, as shown in Figs. 1 and 2, to constitute a fly wheel that is substantially in static balance about its center of rotation. When in this position, the Weights adapt the driving unit 18 to be utilized for the operation of auxiliary a paratus, such as a hoistingreel (not shown that require a steady torque. When the driving unit 18 is utilized for such operations, the pitman 12 is disconnected from the crank 15.

It may be readily seen that the weights 31 and 32 may be secured in a number of combinations of positions to meet a large variation in the degree of unbalance and to adjust the center of the unbalanced mass angularly relative to the crank 15. It is sometimes desirable to have the center of mass of the counter-balancing mechanism lag behind the crank arm in order to compensate for the lag of the pump piston that results from th elasticity of the sucker rods.

From the foregoing description, it may be readily seen that the invention provides a counterbalancing mechanism for neutralizing the gravitational forces inherent in a standard oil-well-pumping apparatus and one that is further adapted to be adjusted to provide the proper amount and phase relation of the balancing mass for the particular operating conditions under which the pumping apparatus may be working.

Although I have described a s ecific embodiment of my invention, it will e obvious to those skilled in the art that various modifications ma be made in the details of construction an in the proportions of the several cooperating parts thereof without departing from the spirit and scope of the invention as I cla'm as my invention:

1. In a counter-balance for oil-well pumps, a crank arm having a hub portion, a counter- Weightintegral with the crank arm, two adjustable counter-weights journalled on the hub portion and disposed to rotate about the axis of the hub portion, and means for securing the adjustable weights in different predeterminedangular positions relative to said first-mentioned weight.

2. A counter-balancing mechanism comprising a weight in the form of a sector of a disc, two weights in the form of sectors .of a disc of substantially one half the width of said first-mentioned weight, said second named weights being disposed to be adjusted angularly relative to the first-mentioned weight to vary the amount of the unbalanced mass of the mechanism.

3. A counter-balancing mechanism comprising a sector weight having an integral hub portion and leaf weights journalled on said hub portion, said leaf Weights being'ad- .justable angularly relative to the sector Weight and adapted tocounter-balance the sector weight when in one position to place the mechanism in static balance about its normal axis of rotation.

4. A counter-balance for oil-Well pumps that comprises a weight of substantially the shape of a sector of a disc, a hub portion formed integral with the weight and having a flange portion, said weight constituting a crank arm and openings in said weight for receiving a crank pin, a pair oi weights that together constitute substantially a duplicate of the first-namedweight, said weights being journalled on the hub portion and disposed to be secured to said flange in selective angular relation thereto.

first-named weight, said adjustable weights being adapted to be turned relative to the first-named weight in a plane adjacent the plane of the first-named weight to vary the unbalanced mass of the mechanism.

8. A counter-balancing mechanism com prising a fixed weight in the form of a sector of a disc disposed-to rotate about its geometrical center,- a pair of adjustable weights each in the form of a sector of a disc of substantially the same radius and thickness as the fixed weight and extending through an are substantially one-half the circumference of the disc, said adjustable weights being disposed to turn abouttheir geometrical centers on the axis of the fixed weight and in a plane adjacent to the plane thereof to vary the counter-balancing effect of the device from zero to substantially twice that of the fixed Weight.

9.'A counter-balancing mechanism compris ng a fixed weight having the shape of a sector of a disc, a hub member formed integral therewith to adapt the Weight to rotate about its geometrical axis, a pair of ad- 5. A counter-balancing mechanism that comprises a sector weight having a hub portion and a pair of leaf weights journalled on said hub portion and disposed in a transverse plane adjacent the sector weight, said leaf weights together constituting substantially a duplicate of the sector Weight, and means for securing the leaf weights to the sector weight in different angularly disposed positions.

6. In a counter-balance for oil-well pumps the combination with a hub portion, a flange formed integrally with the hub portion, a weight also integral with the hub portion to 4. form a crank arm, said weight having a series of crank-pin holes; of a pair of fan leaf weights journalled on the hub portion and disposed to be adjusted angularly relative tosaid crank arm.

7. A counter-balance mechanism comprising a weight in the form of a sector of a disc, a pair of adjustable weights each in the form of a sector of a disc of substantially the radius'and thickness of the first-named weight and of substantially one-half the arc of the 

